Dual-pressure unloader



April I c. w. METZGAR 1,754,331

- DUAL PRESSURE UNLOADER Filed Nov. 21, 1927 s v I f 2 j 7 IN VEN TOR. 7

(F205 fevmjwet? (7661' Patented Apr. 15, 1930 UNITED; STATES I PATENT OFFICE y CHESTER W. METZGAR, F EASTON, PENNSYLVANIA, ASSIGNOR TO INGERSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY DUAL-PRESSURE UNLOADER Application filed November 21, 1927. Serial 1%. 234,698.

This invention relates to compressor unloaders, but more particularly to a dual pressure unloader by means of which the unloader may be controlled or set for operation at different compressor discharge pressures asdesired. a r

The invention is a modification of the dual pressure unloader disclosed in United States Patent No. 1,612,638 granted to me December 28, 1926, and in some respects is an improvement on said device, designed to simplify the apparatus and render it more compact, avoid the use of springs, and enable the device to be electrically controlled from a distance.

The device is illustrated in one of its preferred forms in the accompanying drawing, which is a diagrammatic representation of a compressor and clearance unloader partly in vertical section and partly broken away, only so much of the compressor and unloader being shown as will serve to illustrate the invention. p y e The unloader regulator D may be constructed like the unloader shown in United States Patent No. 1,430,578 granted to me October 3, 1922, for a compressor regulator to whichpatent reference may be made for the details of the regulator and only the principal parts required for an understanding of the present invention will be here described.

Referring to the drawing, a compound duplex compressor is illustrated, having the low" pressure cylinder A, the high pressure cylinder B, and the intercooler B. The compressor discharges into the receiver C and may be driven by the electric motor C.

The unloader regulator D is of the clearance control type and controls clearance valves (not shown) in the valve casings E on the compressor cylinders all as shown in Patent No. 1,430,578. The pipes 1,2, 3 and 4 lead from the regulator D to the valve casings on the compressor cylinders as usual and a movable member preferabl in the form of a lever arm F pivoted at to a portion of the regulator casing is responsive to dis charge or receiver pressure by means of a diaphragm (not shown) in the casing H and apin J. Receiver pressure is led to the diaphragm casing through the pipe L and receiver pressure is also supplied to the regulator for operating purposes through the branch pipe 0. The vent pipe P for the regulator is open to atmosphere. The pilot valve Q, operating in the regulator D and controlling the pipe connections 1, 2, 3 and 4 is pivotally hung from the lever F at the point B and in the operation of the regulator as described in the aforesaid patent, the upward and downward movement of the lever F causes the operation of the clearance valves in the casings E successively in pairs to unload and load the compressor.

.The frame S is conveniently provided with" a bracket T having formed thereon or connected thereto a regulator cylinder U located adjacent or in proximity to the outerend of lever F anda fluid actuated piston V operates in the cylinder U. r A hollow plunger W in the cylinder is actuated in one direction, that is upwardly, by the piston V, and this plunger is weighted by means of the adjustable Weights X, so that the plunger moves downward when pressure fluid is released beneath the piston V. The weights X may be carried on the support or plate Y con.- nected by rods a to the headb of the plunger W. A linkc hung from the end of the lever I F by hook d, passes slidably into the plunger W and forms a loose or lost motion connection between the lever and the regulator plunger. A stop eat the end of the link inside the plunger causes the lever, and link to pick up the plunger and weights and shift or transfer them from the piston V to the end of the lever when pressure fluid is released from beneath'the piston V. The unloader will then not start to unload the compressor until a higher operating pressure is reached. Supply of pressure fluid beneath the regulating piston V will relieve the lever F of the weights as indicated in the drawing. The pressure fluid for the regulating cylinder U may be controlled in any suitable manner but in this instance an electro-magnet f is shown actuating valves 9 and h in the valve casing j, which control the supply and of any suitable or standardcharacter andas shown a weight k on the core 0 engages one end of the lever p pivoted at g to the casing j. The lever arm r carries an adjusting screw 8 adapted to open and close the ball valve 9 as the lever p is rocked. A pin t located between the valves 9' and It causes one to open as the other closes and a spring u bears against valve h. The branch pipe 4) supplies pressure fluid to the valve casing j, and a pipe w connects the casing with the regulating cylinder U. Leads w and :1 connect the magnet f to the mains 2 and 3 and the magnet is controlled by the switch a. c

When the magnet f is deenergized, the weight 12 causes the parts to assume the positions in the drawing with valve 9 closed and valve it open so that pressure fluid is supplied to the regulating cylinder U to maintain the piston V in. raised position. lVhen the magnot f is energized by closing the remote switch a the core 0 is raised which rocks the lever p and changes the positions of valves 9 and hto cut of! the supply and vent the cylinder U through pipe w to atmosphere.

In the operation of the dual pressure regulater, the parts will normally be in the positions indicated in the drawing, with the rights X suspended from the plunger WV. By closing the switch a the cylinder U is exhausted and the weights X are transferred to the link 0 hung from the lever F so that highor receiver ressure. is required to start the operation 0 the unloader.

I claim: 7

1. In a compressor, the combination of a cylinder and compressor piston, an automatic unloaderfor the cylinder having a movable member responsive to discharge, pressure, a regulating cylinder and. fluid actuated .piston therein located adjacent said movable member, a plunger in said regulating cylinder cooperating with the piston, weights continuously carried by the plunger, a loose conmotion between the plunger and said movable member, and means for controlling the sup ply of pressure fluid to said regulating cylinder, whereby the weightsmay be transferred to the movable member andreleased there from.

i 2.. In a compressor, the combination of a cylinder and compressor piston, an automatic unloader for the cylinder having a movable member responsive to discharge pressure, a regulating cylinder and fluid actuated, piston therein located adjacent said movable membar, a. plunger in said regulating cylinder actuated in' one direction by said piston, weights continuously carried by said plunger affording resistance to the pressure fluid actuating the piston, and a loose connection between the plunger and said movable member, whereby the Weights are transferred to the movable member when pressure fluid in the cylinder is released...

3. In a. compressor, the combination of a cylinder and compressor piston, an automatic unloader for the cylinder having a movable member responsive to discharge pressure, a regulating cylinder and fluid actuated piston therein located in proximity to the said movable member, a continuously weighted plunger in said regulating cylinder cooperating with the piston and actuated thereby in one direction, and a lost motion connection between the movable member and the plunger, whereby release of pressure fluid from the regulating piston transfers the weighted plunger to the movable member.

4. In a compressor, the combination of a cylinder, an automatic unloader for the cylinder having a movable member responsive to discharge pressure, weight carrying means, a link on said movable member normally adapted to engage said weight carrying means and pneumatic means for disengaging said link and weight carrying means.

5. In a compressor, the combination of a cylinder, an automatic unloader for the cylinder having a movable member responsive to discharge pressure, weight carrying means, a link on said movable. member normally adapted to engage said weight carrying means and pneumatic means for disengaging said link and weight carrying means comprising a cylinder member and a relatively moveab e piston member, one of said last mentioned members being attached to said weight carrying means.

6. In a compressor, the combination of a cylinder, an automatic unloader for the cylinder having a movable member responsive to discharge pressure, weight carrying means, a link on said movable member normally adapted to engage said weight carrying means and pneumatic means for disengaging said link and weight carrying means, comprising a stationary cylinder and a hollow plunger and piston cooperative with said cylinder, said link member being adapted to pass through said plunger.

7., In a compressor, the combination of a cylinder, an automatic unloader for the cylinder having a movable member responsive to discharge pressure, weight carrying means, a link on said movable member normally adapted to engage said weight carrying means and pneumatic means for disengaging said, link and, weight carrying means and means to control said disengaging means.

8. In a compressor, the combination, of a cylinder, an automatic unloader for the cylinder having a movable member responsive to discharge pressure, weight carrying means, a link on said movable, member normally adapted to engage said weight carrying means and pneumatic means for disengaging said link and weight carry means, and electromagnetic means. for controlling said disengaging means. 

